Method and assembly for separating solids from gaseous phase

ABSTRACT

The invention relates to a method for separating materials of two different phases from one another and an assembly for implementing the method. According to one embodiment of the invention, the second phase having the material in suspended or dispersed form is separated from the first phase by centrifugal force. At least one separator comprises a multiport cyclone into which the material flow is passed via an infeed nozzle having an annular cross section.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/FI99/00671 which has an Internationalfiling date of Aug. 12, 1999, which designated the United States ofAmerica.

BACKGROUND OF THE INVENTION

The invention relates to separation of two phases from each other, aswell as an assembly suited for implementing said method. In particular,the invention concerns a method according to the preamble of claim 1 forseparating solids and/or liquids from gas flows or, respectively, forseparating solids from liquid flows. According to the present method, agas-phase flow carrying, e.g., a catalyst or other solids or a liquidphase is passed to a separating means, wherein the other phase is thenseparated from said gas phase under the effect of a centrifugal force.To separate solids from a liquid-phase flow, the liquid flow is passedin a similar manner to a separating apparatus, wherein the solids areseparated from the liquid under the effect of a centrifugal force.

The invention also relates to an apparatus according to the preamble ofclaim 15, suitable for separating solids and/or liquids from gas/liquidflows in fluidized-bed equipment.

Embodiments of highest commercial value used for separating two phasesfrom each other are fluidized-bed reactors. Generally, fluidized-bedreactors are employed in the hydrocarbon conversion processes and energygeneration. In these apparatuses a catalyst or similar solids-containingmaterial capable of improving heat transfer or material fluidization iskept in a fluidized state by means of a gas-phase hydrocarbon or fluegas flow. Subsequently, the solids are separated from the gas flow bymeans of a cyclone.

The most generally used fluidized-bed reactor is a bubbling-bed reactorin which the linear flow velocity of the fluid medium is typically from5 to 10 times the minimum fluidization velocity that can maintain themain portion of the solids in the fluidized bed of the reactor, wherebyno significant amount of the solids can escape the reactor along withthe hydrocarbon and flue gas flow. The term minimum bubbling velocity isdefined as the linear gas flow velocity at which a portion of the gasflow begins to pass through the bed in the form of bubbles. This minimumbubbling velocity is dependent on the properties of the fluidizing gasand the solids involved.

When the gas flow velocity is increased above the minimum bubblingvelocity, the top of the fluidized bed becomes less defined, in fact,being transformed into a gradient zone in which the solids contentdecreases upstream. At sufficiently high flow velocities, a fluidizedflow is achieved in which practically all particulate solids areentrained in the gas flow that keeps up the fluidized state. Then, thesolids separated by cyclones from the gas flow must be returned to thebottom part of the reaction space in order to maintain the mass balanceunchanged.

As mentioned, the method and assembly according to the invention can beused, e.g., in processes employed for treating hydrocarbons. Examples ofsuch processes include catalytic and thermal cracking, dehydrogenation,Fischer-Tropsch synthesis, manufacture of maleic acid anhydride andoxidizing dimerization of methane.

An application of the fluidized-bed reactor commonly used in energygeneration is a boiler in which the fluidized material such as sandand/or solid fuel particles are fluidized with the combustion air flowand the flue gas released in the process. Also a liquid- or gas-phasefuel can be used. Circulating fluidized-bed (CFB) reactors of both thebubbling fluidized-bed and the entrained fluidization technique areconventionally used in the art. In these, the solids and unburntparticles are removed from the flue gas flow by means of cyclones. Inthis context, the term entrained fluidization refers to fluidizationwhich takes place in both the turbulent fast fluidization range as wellas the pneumatic transport range.

Hydrocarbon conversion processes are run using fixed-bed reactors andfluidized-bed reactors (fluidized catalytic reactors). In the presentcontext, the term “fluidized catalytic process equipment” is used torefer to equipment used in processes having a fine-grained pulverizedcatalyst suspended, e.g., in a slowly upward rising gas flow, whereinthe catalyst promotes the occurrence of desired reactions.

One of the most widely employed fluidized-catalyst reactor systems inthe art is the FCC equipment, that is, fluidized-catalyst crackingequipment, comprising chiefly a riser pipe acting as a reactor operatedin the fast-fluidization flow state and a regenerator operated in thedense-phase bubbling bed state.

In fluidized-bed reactors, the particulate matter of the suspendedsolids and the product gas are separated from each other in cyclonesutilizing the effect of the centrifugal force. Typically, a number ofcyclones must be connected in series along the gas flow in order toimprove the overall collection efficiency, because single cyclones ofnormal construction exhibit inferior separation capability for particlessmaller than 15 μm. Herein, a cyclone is rated effective if it canseparate these small-diameter particles from the gas flow.

In addition to applications related to fluidized-bed reactors, cyclonesare also used for, e.g., separating liquid droplets in steam systems,solids from flue gases of drying processes, phase separation ontwo-phase flows (demister equipment), separation of solids from gases(dust separators) and as hydrocyclones serving in the coarse separationof solids from waste waters.

Cyclone separators have either a coiled or spiralled structure in whichthe particulate matter suspension is directed as a tangential flow intothe cylindrical section of the cyclone, whereby the catalyst particlesare driven apart from the gas to a close distance of the cyclone innerwall when the flow typically circulates about 7-9 revolutions within thecylindrical section of the cyclone and the conical section forming acontinuation thereof. Also axial cyclones are known in which the gasflowing through a pipe is forced into a circulating motion by means ofvanes, whereby the solids under the centrifugal force are driven againstthe pipe wall and separated thereon from the gas flow.

The most common cyclone type is a single-port spiralled cyclone calledthe Zenz cyclone, in which the proportions of the different parts of thecyclone are standardized, thus permitting the dimensioning of thecyclone to be based on graphs and computational formulas. The collectionefficiency of this cyclone can be enhanced by a large number of flowrevolutions in the cyclone chamber, high flow rate at the inlet nozzle,higher density of solids, narrower inlet nozzle port and lower viscosityof the gas.

In the preseparation cyclone of a fluidized-catalyst cracking unit,tests have shown the gas residence time to be in the order of 1.0-2.0 sfrom the riser top to the cyclone outlet, after which the catalyst willfurther stay in the separation vessel at an elevated temperature for5-40 s. During this time, valuable compounds will be lost as aconsequence of thermal reactions. Resultingly, gasoline products will beconverted by thermal cracking into combustible gases, particularlyhydrocarbons of the C₂ type. Other byproducts of thermal reactions aredienes, such as butadienes, which in the alkylation unit cause asignificant increase in the acid consumption. Pentadienes in turn areparticularly reactive, whereby their detrimental effect is evidenced asa reduced oxidation resistance of FCC gasoline. Further problemshampering the use of conventional FCC units are related to their poorcontrol of reaction time and the erosion of the catalyticparticles/circulating solids and the reactor structures.

The problems are mostly related to such essential parts of the equipmentas the separation units of gases from solids/catalysts, that is,cyclones, which in most cases are implemented as single-port units.Herein, the term single-port cyclone refers to a cyclone constructionhaving only one inlet nozzle for feeding the gas flow into the cyclone.To achieve the desired through-flow capacity, a plurality of these unitsare generally connected in parallel and then two or three in series.

In addition to being complicated and expensive, conventional cycloneconstructions require a large footprint. Furthermore, the interior spaceof the cyclones must be lined with a ceramic compound to preventerosion.

It is an object of the invention to overcome the disadvantages describedabove and to provide an entirely novel type of method and assembly forseparating solids from a gas flow.

The goal of the present invention is attained by replacing at least oneof the conventional cyclones of a fluidized catalytic process with acyclone having multiple inlet openings (also known as a multi-inletcyclone or a multiport cyclone), or alternatively, with a plurality ofsuch multiport cyclones connected in series in a number of one or more.Herein, the term multiport cyclone is used to make reference to cycloneconstructions having at least two, preferably at least 4 to 8 inletports for directing the gas flow to impact on the internal wall of thecyclone as an essentially tangential flow. The collection efficiency ofa multiport cyclone can be made higher at low flow speeds and itsstructure is simpler and cheaper than that of conventional cyclones.Also the footprint required by the multiport cyclone is smaller.

A multi-inlet cyclone is mentioned the first time in a patentpublication filed by E. I. Du Pont de Nemours and Company in 1974 (U.S.Pat. No. 3,969,096). Cited patent publication describes a cycloneseparator having multiple-vaned gas inlet openings, said cyclone servingto separate suspended solid particles from internal combustion engine(in a car) exhaust gases.

However, E. I. Du Pont de Nemours and Company fails to present in thepatent publication a theory capable of explaining why a multiportcyclone has a good collection efficiency at a low pressure drop.According to their hypothesis, the inlet guide vanes direct the incominggas flow into the cyclone separator in sheetlike streams close to theinner wall of the cyclone shell, whereby the entrained particles need totravel a shorter distance prior to separation. Furthermore, theinventors assume that said sheets of inlet streams form a cleaner massboundary between the downward and upward spiralling inlet streams,whereby the flow has a reduced tendency to form eddies. As stated in theapplication, reducing the eddy formation decreases the velocity-slowingdrag on the inbound stream thus increasing the separating efficiency.

SUMMARY OF THE INVENTION

The separator equipment, or cyclones, used in the present inventioncomprise a cyclone chamber having an at least essentially uprightaligned center axis and an advantageously essentially circular crosssection of its internal space, whereby the separation chamber isrotationally symmetrical with respect to its center axis. To theseparation chamber is connected an infeed nozzle of process gases, saidnozzle having an essentially circular cross section centered about thecenter axis of the chamber. Further, the separation chamber includes acenter pipe arranged therein for removal of gases and a downward returnleg for the recovery of solids separated from the gas phase. Theseparation chamber is equipped with a set of guide vanes forming alouver which forces the gas to be treated into a stream circulatingclose to the inner wall of the cyclone chamber, thus effecting theseparation of solids from the gas phase under the effect of thecentrifugal force.

Advantageously, the assembly is comprised of cylindrical shells placedco-axially within each other, whereby the intershell channels withannular cross-section act as the fluidization space and the downwardreturn leg of the reactor. The catalyst or solids are separated from thegas-phase suspension exiting the reactor by means of a multiport cycloneadapted immediately above the axially annular intershell flow channel.

Herein, the term “solids” refers to the material forming the suspensionin the reaction space. Typically, the solids consist of catalystparticles if the reactor is employed in catalytic reactions. When thereactor is used in physical or thermal processes, the solids may beeither inert particulate matter serving to transfer beat or materialinto the reaction space or out therefrom, or alternatively, particles ofa solid fuel. The catalyst is selected according to the process beingrun.

The multiport cyclone is advantageously connected to the upper part ofthe reaction space. The material to be treated in the cyclone is passedvia multiple inlet openings into the cyclone chamber. The infeedopenings can be located symmetrically or asymmetrically about the centeraxis of the cyclone. Advantageously, the openings are disposedsymmetrically, and the riser space is given an annular cross section,whereby the flow is homogeneous over the entire cross section of theflow channel. In this case, the cyclone is equipped with flow guidevanes serving to the force the flow into the spiral motion required forthe centrifugal separation. Typically, the guide vanes are adapted in acircularly louvered fashion about the perimeter of the cyclone chamberinterior wall so as to form a louver comprising a plurality of parallelinlet channels for the entering gas flow. Thus, the infeed nozzle of amultiport cyclone comprises means for deflecting the infeed flow thatenters the cyclone radially. Such means may be formed by, e.g., guidevanes adapted to the upper part of the cyclone so that at least someportion of the vane area deflecting the impinging flow causes the flowto assume an essentially high velocity component directed toward thecyclone center axis thus serving to direct the gas stream from theperimeter of the cyclone toward the center of the cyclone.

In a CYMIC circulating bed boiler developed by Kvaerner Pulping Oy(formerly Tampella Power Oy), such a multiport cyclone is used to removeentrained particles of the fluidized bed material from the flue gasesand to return the particulate matter back to the boiler. The cyclone isdisposed in the interior space of the boiler and is cooled with water.

It is possible to adapt a second multiport cyclone in the interior spaceof a first multiport cyclone or, alternatively, of a conventionalcyclone, too, inasmuch the gas flow in the cyclone is symmetrical thuspermitting the distribution of flow in a symmetrical manner to the guidevane system of the secondary cyclone. This kind of arrangement offersadvantageous flow and construction properties, because the lowerconcentration of catalyst in the secondary cyclone permits the lattercyclone to be operated at a higher flow velocity than the precedingupstream cyclone. Depending on the available factory space andcollection efficiency, a desired number of cyclones can be connected inseries.

In a preferred embodiment of the invention, the infeed nozzle ofessentially annular cross section used according to the invention fordistributing the gases to be treated is implemented so that the meansfor deflecting the radially entering gas flow are extended in the radialdirection outside the exterior perimeter of the cyclone. Furthermore, ina particularly advantageous embodiment of the invention, said means,such as the infeed nozzle comprising the guide vane system extends inthe exterior space of the cyclone from the top level of the cyclonedownward along the outer perimeter of the cyclone shell. Then, theportion of the guide vane system located on the outside surface of thecyclone and directed downward on the same can be adapted to direct theflow entering the cyclone in the upward direction from the precedingcyclone that surrounds the said cyclone. Flow direction in the presentcontext is used for making reference to, e.g., flow guidance,stabilization and/or deflection. The guide vane system may also beplaced only partially inside the inlet channel or, alternatively,entirely or only partially inside the cyclone.

In a preferred embodiment of the invention, the downward return legs ofthe concentrically adapted cyclones are placed in a similar mannerco-axially. In a further preferred embodiment of the invention having atleast two multiport cyclones adapted concentrically, the cyclones areadvantageously designed so that the guide vane system of any innercyclone is always located above the guide vane system of therespectively upstream preceding outer cyclone.

Accordingly, the goal of the invention is attained by adapting at leastone multiport secondary cyclone inside a primary cyclone or anotherpreceding secondary cyclone.

More specifically, the method according to the invention ischaracterized by what is stated in the characterizing part of claim 1.Furthermore, the assembly according to the invention is characterized bywhat is stated in the characterizing part of claim 15.

The present invention provides significant benefits. Accordingly, theequipment construction according to the invention, which is based on theuse of a multiport cyclone, gives significant advantages in flowdynamics and process engineering over conventional arrangements andgenerally used single-port cyclones. This is because of the fact that inconventional single-port cyclones, the solids flow impinges on thecyclone inner wall as a homogeneous gas-suspended jet of high flowvelocity which in primary cyclones is typically in the range 20-25 m/s,in secondary cyclones about 35 m/s, and in tertiary cyclones about 40m/s. The flow rate of the impinging jet must be high, because thecyclone inlet nozzle width (et width) is generally, e.g., instandardized Zenz cyclones about one-fourth of the cyclone diameter, andthe particulate matter must be brought over the entire width of theimpinging jet close to the cyclone inner wall in order to achieveseparation of the solids from the gas flow. In this type of cyclone, thepoint most susceptible to erosion is the area of the cyclone inner wallreceiving the jet impact of the suspended catalyst particles.

By contrast, in the construction according to the invention, the erosionproblems are eliminated by improved flow dynamics: the conventionalsingle large-volume inlet flow of solids is divided into a plurality ofsmaller-volume mass flows impinging on the internal wall of themultiport cyclone, whereby the erosive effect is distributed over alarger area. By virtue of the multiport construction, the cyclone inletports can be made narrow, whereby the catalyst layer becomes shallow,and the flow velocity at any inlet port may be essentially smaller thanin conventional single-port cyclones in which reduction of the inletport width would require an increased channel height, resulting in ahigher cyclone and requiring an infeed channel of an elongated andclumsy shape. The possibility of using a reduced cyclone inlet flowvelocity contributes to a further lowered erosion rate, which accordingto published references is dependent on the flow velocity by a power of4 to 5.

In tests carried out at room temperature, a cyclone according to theinvention with 465 mm diameter with full-area inlet ports and straightvanes has demonstrated a collection efficiency of 99.99% at 5.6 m/sinlet flow velocity when the cross-sectional mass flow rate of thecatalyst according to differential pressure measurements was over 200kg/m²s. In a conventional Zenz cyclone with compatible dimensions andflow rates, the collection efficiency was 99.10% as computed by particlesize fractions. A comparison of these collection efficiencies makes itclear that the novel cyclone with multiple narrow inlet ports accordingto the invention offers a superior efficiency when the design goal is toavoid high flow velocities leading to erosion.

In a preferred construction according to the invention having thereactor riser pipe (hereafter, shortly a riser) connected directly tothe cyclone inlet pipe, an accurately controllable residence time isachieved, because the catalyst is made to enter the cyclone from eachpoint of its infeed pipe simultaneously. Hence, a cyclone according tothe invention can be designed for a volume about half of that of astandard cyclone. By placing the cyclones concentrically inside oneanother, the valuable interior volume of the cyclone pressure vessel canbe reduced as compared to arrangements having the cyclones placed in aparallel or superimposed manner in the interior space of the pressurevessel. Since a cyclone according to the invention may have a shorterconstruction owing to its improved flow dynamics, its height and,respectively, retention time can be, e.g., halved from the correspondingvalues of a standard cyclone. Resultingly, the possibility of undesiredthermal reactions is reduced. Moreover, the product can be cooleddirectly in the discharge pipe of the cyclone if so required.

According to a first preferred embodiment of the invention, themultiport cyclone is used for separating catalyst from the product gasesof a fluidized catalytic cracking (FCC) process. The multiport cyclonemay also be employed in the regenerator equipment of an FCC unit forseparating the regenerated catalyst from the coke combustion gases.

Other suitable fluidized catalytic processes are, among others:catalytic reforming, oxidizing dimerization of phthalic acid anhydride,maleic acid anhydride or methane, Fischer-Tropsch synthesis,chlorination and bromination of methane, ethane and other hydrocarbons,and conversion of methanol into olefines or gasoline.

Separation of solids is carried out using a plurality (e.g., 2-10, mostappropriately 2-5) of cyclones connected in series. By virtue of theirstructure, the cyclones used in the invention, of which at least one isa multiport cyclone, can be adapted concentrically inside one another,e.g., so that the downward return leg of the any one cyclone in thedownstream series of cyclones is adapted to the interior of the downwardreturn leg of the preceding cyclone. Owing to the longitudinally-stackedcoaxial placement of the cyclones within the pressure shell, asignificant volume reduction is attained with respect to conventionalcyclone constructions requiring side-by-side placement of the cyclones.A multiport cyclone can be made with a larger diameter than aconventional cyclone; the diameter of multiport cyclones may be over onemeter, even up to several meters, whereas the diameter of a conventionalcyclone is generally limited to 1 m maximum. Yet, the diameter of thereaction vessel need not be increased in the embodiment according to theinvention, but instead, may even be made smaller.

The cyclone infeed nozzle can be formed from the intershell spaceremaining between two concentrically adapted cylindrical or partiallyconical envelope surfaces, whereby said annular space may be dividedinto parallel flow segments by means of axially extending baffles. Theparallel flow segments can be implemented by mounting longitudinallyaligned baffles radially between the two coaxial, cylindrical envelopesurfaces. Almost an equivalent result is obtained by constructing theinfeed nozzle with the annular cross section from a set of parallelinfeed channel tubes mounted equidistantly spaced in a circular fashion.

The guide vanes of the cyclone are adapted in a circularly louveredfashion about the perimeter of the cyclone chamber wall, partially orentirely inside the riser channel so as to form a louver comprising aplurality of parallel inlet channels for the entering gas flow.

The cyclone(s) according to the invention either is/are connecteddirectly to the riser channel (shortly, riser) of a fluidized catalyticprocess reactor, which is a preferred embodiment of the invention, oralternatively, the infeed nozzle(s) of the cyclone(s) is/are adapted tocommunicate with the gas space of a fluidized catalytic process reactoras is the case with conventional arrangements.

In a preferred embodiment of the invention having the means, which areprovided for deflecting the flow entering the cyclone in a radialdirection, arranged to extend radially outward to the outer space of thecyclone, the flow can be controlled effectively already prior to itsentry into the cyclone. Moreover, in a particularly advantageousembodiment of the invention, in which said means extend downward fromthe top level of the cyclone, the flow control effect may be furtheraugmented and the flow control started earlier than in conventionalconstructions. Resultingly, it is possible to control efficiently and atan early stage the flow which leaves the vortex zone of the precedingouter cyclone and is directed upwards. Owing to the efficient flowcontrol arrangement, the flow can be passed in a desired state of flowinto the inner cyclone, unaffected by any possible irregularities in theflow pattern of the outer cyclone. Furthermore, the powerful flowcontrol effect exerted by the guide vane system, particularly in itsupright portion outside the inner cyclone, facilitates an exceptionallygood degree of preseparation between the outer and inner cyclones of theseparator assembly.

As the inlet flow to the inner cyclone may already initially have atangential velocity component, it may be advantageous not to extend theguide vanes up to the outer edge of the inlet channel of the innercyclone.

A further benefit is gained therein that the upright deflecting orguiding means adapted on the outer perimeter of the cyclone, said meanscomprising a tubular outer envelope for forming a gas flow channel inthe intershell space between said outer envelope and said outerperimeter of said inner cyclone, facilitates an advantageous concentricplacement of the multiport cyclones inside one another so that the guidevane system of each successively inner cyclone is located above guidevane system of the respectively preceding outer cyclone. Herein, it iseasy to realize a construction in which the downward return leg of theinner cyclone contains a column of solids column extending higher thanthe solids column formed in a similar manner from the separated productsolids in the downward return leg of the outer cyclone. The solidscolumn must be maintained if the pressure in the interior space of thecyclone is lower than the ambient pressure about the bottom end of thecyclone downward return leg. Respectively, the height difference betweenthe tops of the solids columns is necessary in order to compensate forthe difference between the pressure levels in the interior spaces of thecyclones when the bottom ends of the cyclone downward return legs exitin the same space. The pressure difference between the interior spacesof the cyclones is principally created by the pressure drops occurringin the guide vane systems or similar deflecting means as well as by thepressure losses occurring in the flow channels and due to the changes ofthe flow velocity. The pressure difference is compensated for throughthe different hydrostatic pressures over solids columns of differentheights accumulated in the downward return legs of the cyclones. In thismanner, the return of the solids to the cyclone bed can be implementedusing the embodiment described above.

Next, the invention will be examined with the help of exemplifyingembodiments by making reference to the appended drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a prior-art cyclone.

FIG. 1B shows a first embodiment of a cyclone according to theinvention.

FIG. 2A shows a prior-art cyclone.

FIG. 2B shows a second embodiment of a cyclone according to theinvention.

FIG. 3A shows a prior-art cyclone.

FIG. 3B shows a second embodiment of a cyclone according to theinvention.

FIG. 4 shows an embodiment of a cyclone according to the inventionassembled so that a higher hydrostatic pressure difference can becreated between the inner and the outer cyclone than that occurring inthe embodiment of FIG. 3B. Furthermore, the guide vane system herein isadapted to extend only partially into the interior of the inlet channel,whereby the tangential velocity component imposed by the primary cycloneon the flow can be utilized.

EXAMPLE 1

In FIGS. 1B and 2B is shown a first and a second preferred embodiment ofthe invention suitable for use in conjunction with a fluidized-bedcatalytic cracking unit, FCC. The FCC unit includes two reactors, onereactor of the circulating fluidized bed type and a bubblingfluidized-bed regenerator. Conventional constructions used for the samepurpose are illustrated in FIGS. 1A and 2A.

FCC Reactor

In FIG. 1B is shown a cyclone construction according to the invention,while FIG. 1A shows a conventional cyclone arrangement having twocyclones (primary and secondary cyclones) connected in series directlyto the riser of an FCC reactor. Obviously, the number of cyclones in theseries connection may be greater or smaller than two.

Function of Prior-art Cyclone Arrangement

The mixture of the prefluidization gas with the evaporated phase ofreacted and still reacting hydrocarbon is passed in gas phase upwardalong a riser 12, whereby the entrained catalyst is carried to a primarycyclone 13 adapted to the interior space of the reactor vessel 15. Thesolids are separated from the gas phase on the walls of the reactorchamber and fall therefrom into the downward return leg of the primarycyclone 13. From the return leg, the catalyst is transported forwardinto a hydrocarbon separation section and a regenerator. The gas flowentering the primary cyclone 13 exits the cyclone 13 via its center pipeinto a secondary cyclone 14. The particulate matter is separated fromthe gas by impinging on the chamber walls, then falling therefrom intothe return leg of the secondary cyclone 14. From the secondary cyclone14, the gas passes into a possible collection chamber and is dischargedfrom the reactor vessel 15 via an outlet nozzle 16.

Cyclone Assembly According to the Invention and its Function

In the assembly shown in FIG. 1B, a reactor 11 comprises a primarycyclone and a secondary cyclone plus a riser 1 for passing the reactionmixture flow into the primary cyclone and a discharge pipe 10 forpassing the gas flow out from the secondary cyclone and discharging thesame from the entire reactor assembly 11. The primary cyclone includesan annular space 2 formed to the upper end of the riser 1 in theinterior space of a reactor 11, a guide vane system 3 adapted at leastto the upper part of said annular space 2 with a chamber 4 situatedbelow said guide vane system for forcing the reaction mixture flowpassing via said guide vane system 3 into a vorticously rotating flowthat sweeps along the interior wall of said chamber 4 and a downwardreturn leg 5 connected to the lower part of said chamber 4.

The secondary cyclone is adapted to the interior space of the primarycyclone and comprises a center pipe 6 that forms an axially annular flowchannel and passes the gas flow introduced into the primary cyclone fromthe primary cyclone to the secondary cyclone, a guide vane system 7connected to said axially annular flow channel formed by said centerpipe 6 and a chamber 8 connected to said guide vane system 7, all ofthese components serving to force the gas flow entering said secondarycyclone into a vorticously rotating motion that sweeps along theinterior wall of said chamber 8. The secondary cyclone also includes areturn leg 9 that extends downward from said chamber 8 and isadvantageously disposed co-axially in the interior space of said returnleg 5 of said primary cyclone.

In the operation of the above-described assembly, the mixture of theprefluidization gas with the evaporated phase of the reacted and stillreacting hydrocarbon is passed in gas phase upward along a riser 1,whereby the entrained catalyst is carried with the gas to an annularspace 2 adapted to the interior space of the reactor 11, wherefrom itfurther rises upward to the guide vane system 3 of the primary cyclone.The guide vane system 3 serves to induce a vorticous flow in which theentrained particles are separated from the gas phase by impinging underthe centrifugal force on the interior wall of the chamber 4 and fallingtherefrom into the downward return leg 5 of the primary cyclone. Fromthe return leg 5, the catalyst travels further into a hydrocarbonseparation section and a regenerator. The gas flow entering the primarycyclone leaves the cyclone via the center pipe 6, wherefrom the flowrises further along the channel of annular cross section into the guidevane system 7 of the secondary cyclone. The particles are separated fromthe gas phase by impinging on the interior wall of the cyclone chamber 8and falling therefrom into the downward return leg 9 of the secondarycyclone. The return leg 9 of the secondary cyclone is advantageouslyadapted into the interior space of the primary cyclone return leg 5. Thegas flow passed into the secondary cyclone leaves the cyclone and thereactor 11 via an outlet nozzle 10.

FCC Regenerator

In FIG. 2A is shown a conventional cyclone construction and FIG. 2Bshows a cyclone assembly according to the invention, respectively, botharrangements having two cyclones (a primary cyclone and a secondarycyclone) connected in series in the interior space of an FCC regeneratorvessel. The number of series-connected cyclones may be varied so as tobe either greater than two or, alternatively, comprising only onecyclone or a plurality of parallel-connected cyclones. Since aconventional cyclone can have a diameter of about 1 m maximum, generallymore than one of such conventional cyclones must be connected inparallel depending on the.

Conventional Cyclone Arrangement

Herein, the inlet air which is passed through a bottom grate 27fluidizes the catalyst contained in the regenerator 28 in a bubbling-bedcondition and simultaneously imports oxygen to the coke combustionreaction. The gas with the suspended catalyst particles is next passedinto a primary cyclone 29 adapted to the interior space of a regenerator28. The particulates of the flow are separated from the gas phase byimpinging on the interior wall of the separation chamber and fallingtherefrom into the downward return leg 29 of the primary cyclone. Fromthe return leg, the catalyst travels further back into the fluidizedbed. The gas flow entering the primary cyclone 29 leaves the cyclone 29via the center pipe passing into a secondary cyclone 30. The particlesare separated from the gas phase by impinging on the interior wall ofthe cyclone chamber and falling therefrom into the downward return legof the secondary cyclone 30. From the secondary cyclone 30, the gas flowpasses further into a collection chamber and finally leaves the reactorvia an outlet nozzle 31.

Cyclone Assembly According to the Invention and its Function

In the assembly shown in FIG. 2B, a regenerator 18 comprises a primarycyclone and a secondary cyclone as well as a grate 17 for passing airinto the regenerator 18 and a discharge nozzle 26 for passing the gasflow out from the secondary cyclone and simultaneously from the entireregenerator 18. The primary cyclone includes a guide vane system 19adapted at least to the upper part of the cyclone chamber in theinterior space of the regenerator 18 and a chamber 20 situated belowsaid guide vane system 19, said guide vane system 19 serving to forcethe gas flow entering the chamber into a vorticously rotating flow thatsweeps along the interior wall of said chamber. The primary cyclone alsoincludes a downward return leg 21 connected to the lower part of saidchamber 20.

The secondary cyclone is adapted to the interior space of the primarycyclone and comprises a center pipe 22 that forms an axially annularflow channel and passes the gas flow introduced into the primary cyclonefrom the primary cyclone to the secondary cyclone, a guide vane system23 connected to said axially annular flow channel formed by said centerpipe 22, and a chamber 24 connected to said guide vane system 23, all ofthese components serving to force the gas flow entering said secondarycyclone into a vorticously rotating motion that sweeps along theinterior wall of said chamber 24. The secondary cyclone also includes areturn leg 25 that extends downward from said chamber 24 and isadvantageously disposed co-axially in the interior of said return leg 21of said primary cyclone.

In the operation of the above-described assembly, the inlet air passedthrough a bottom grate 17 fluidizes the catalyst contained in theregenerator 18 in a bubbling-bed condition and simultaneously importsoxygen to the coke combustion reaction. The gas flow with the suspendedcatalyst particles rises into a guide vane system 19 formed in theinterior space of the primary cyclone. The function of the guide vanesystem 19 is to induce a vorticous flow in which the particles areseparated from the gas phase by impinging under the centrifugal force onthe interior wall of the chamber 20 and falling therefrom into thedownward return leg 21 of the primary cyclone. From the return leg 21,the catalyst is passed back into the fluidized bed. The gas flowentering the primary cyclone leaves the cyclone via the center pipe 22,wherefrom the flow rises further along the channel of an annular crosssection into the guide vane system 23 of the secondary cyclone. Theparticles are separated from the gas phase by impinging on the interiorwall of the cyclone chamber 24 and falling therefrom into the downwardreturn leg 25 of the secondary cyclone. The return leg 25 of thesecondary cyclone is advantageously adapted into the interior space ofthe primary cyclone return leg 21. From the secondary cyclone, the gasflow leaves the cyclone and the regenerator via an outlet nozzle 26.

EXAMPLE 2

This example elucidates the use of a multiport cyclone in conjunctionwith a conventional single-port cyclone. FIG. 3A shows a conventionalconnection between a primary and a secondary cyclone. Respectively, FIG.3B shows a connection according to the invention in which the multiportcyclone is adapted entirely to the interior space of the single-portcyclone. The adaptation of the multiport cyclone inside the single-portcyclone is made possible by the symmetrical distribution of gas flow inthe interior space of the cyclone, thus permitting the flow to bedivided symmetrically to the guide vane system of the secondary cyclone.

The assembly shown in FIG. 3B comprises a single-port primary cyclonechamber 46, a nozzle 40 passing the reaction mixture flow into saidcyclone chamber 46, a return leg 44 extending downward from said cyclonechamber 46 and a multiport secondary cyclone adapted to the interiorspace of said cyclone chamber 46. The secondary cyclone comprises acenter pipe 41, a guide vane system 42 connected to said center pipe 41,a cyclone chamber 43 following said guide vane system 42 in thedownstream direction of the gas flow, a return leg 47 extending downwardfrom said cyclone chamber 43 and a discharge nozzle 45 extending upwardfrom said cyclone chamber 43.

While the assembly shown in FIG. 4 is otherwise similar to that of FIG.3B, herein the secondary cyclone is adapted partially above the primarycyclone so that a higher hydrostatic pressure difference can be providedbetween the solids columns contained in the return leg 44 and the returnleg 47. Furthermore, the secondary cyclone guide vane system 42 extendsonly partially to the interior of the center pipe 41.

What is claimed is:
 1. A method for separating two phases from eachother, said method comprising passing a material flow of a process,which material flow contains material in a first phase and material in asecond suspended or dispersed phase, into first separating means and,subsequently, into at least second separating means, wherein thematerial in the suspended or dispersed phase is separated from thematerial in the first phase under the effect of a centrifugal force, andat least one unit of the second separating means is a multiport cyclonewhich is adapted inside the first separating means and into whichcyclone the material flow to be treated is fed via an infeed nozzlehaving an annular cross section, wherein a multiport cyclone is used assaid first separating means and wherein the material flow to be treatedis a liquid flow containing solids to be removed.
 2. Method according toclaim 1, characterized in that a plurality of series-connected cyclonesare used for separating the material of said second phase from thematerial of said first phase.
 3. Method according to claim 2,characterized in that therein are used from 2 to 5 series-connectedcyclones having the downward return leg of any one cyclone in thedownstream series of cyclones adapted to the interior of the downwardreturn leg of the preceding cyclone.
 4. A method according to claim 1,wherein downward return legs of at least two successive series-connectedcyclones are adapted to discharge the solids being separated into acommon space.
 5. Method according to claim 4, characterized in that thecompensation of the pressure difference between the interior spaces ofthe cyclones connected successively in series and adapted to returntheir solids fraction into the same space is accomplished by way ofmaintaining solids columns of different heights in the downward returnlegs of said cyclones.
 6. Method according to claim 1, characterized inthat the material flow is passed into said multiport cyclone via saidinfeed nozzle so that the flow entering the interior space of themultiport cyclone from the exterior of the cyclone is guided anddeflected with the help of deflecting means adapted to said infeednozzle so as to be located entirely or at least partially to theexterior side of the cyclone.
 7. A method according to claim 1, whereinthe material flow is passed into said multiport secondary cyclone sothat the flow is directed to travel upward from a primary cyclone towarda top edge of the secondary cyclone with the help of deflecting and/orguiding means adapted to the exterior surface of the secondary cyclone,said deflecting and/or guiding means including a tubular guiding elementthat may contain guide vane members for guiding and deflecting theupright travelling flow.
 8. Method according to claim 7, wherein thematerial flow is passed from said multiport primary cyclone into saidmultiport secondary cyclone so that with the help of deflecting and/orguiding means adapted to the exterior surface of the secondary cyclone,the flow is directed to travel from below first guide vane means of saidprimary cyclone to second guide vane means of said secondary cyclonethat is located above the first guide vane means of said primarycyclone.
 9. An assembly for separating a liquid and/or solids from amaterial flow in fluidized catalytic process equipment, said assemblycomprising: first and second separating means, each having anessentially upright aligned separating chamber (4, 8; 20, 24; 43, 46),said second separating means being adapted inside said first separatingmeans, a first infeed nozzle (1; 17; 40) of the material flow to beseparated, said first infeed nozzle being connected to said firstseparating means; an outlet nozzle (10; 26; 45) connected to said secondseparating means for discharging the flow of the separated material fromsaid separating means, and said second separating means being providedwith a guide vane system (3, 7; 19, 23; 42) serving to force thematerial flow to be treated into a vorticously rotating motion thatsweeps along the interior wall of said separating chamber (4, 8; 20, 24;43) in order to separate the liquid and/or solids from the material flowunder the effect of a centrifugal force, wherein: said first separatingmeans is a multiport cyclone; and said guide vane system includes anupright portion outside an inner cyclone, the upright portion extendingdownward from a top level of the inner cyclone to provide flow controlat an early stage.
 10. Assembly according to claim 9, characterized inthat the cross section of each separating chamber (4, 8; 20, 24; 43, 46)is essentially circular as taken at right angles to the vertical centeraxis of inner wall of the chamber.
 11. Assembly according to claim 9,characterized in that said guide vane system (3, 7; 19, 23; 42)comprises radially outward oriented baffles which are adapted about theupright center axis of said separating chamber (4, 8; 20, 24; 43) so asto divide the passageway of the material flow being treated to saidseparating chamber (4, 8; 20, 24; 43) into parallel segmental flowchannels.
 12. An assembly according to claim 11, wherein said parallelsegmental flow channels are formed by spanning radial baffle platesbetween two concentrically mounted cylindrical shells, said baffleplates being aligned parallel to the longitudinal axis of a reactorspace.
 13. An assembly according to claim 9, wherein at least saidsecond separating means adapted inside said first separating meanscomprises a plurality of second infeed nozzles (2, 6; 22; 41) ofessentially annular cross section for feeding said material flow intosaid guide vane system (3, 7; 23; 42) and therefrom further into saidseparating chamber (4, 8; 20, 24; 43).
 14. An assembly according toclaim 13, wherein said plurality of second infeed nozzles (2, 6; 22; 41)of essentially annular cross section are formed by parallel infeedchannel tubes equidistantly spaced in a circular fashion.
 15. Anassembly according to claim 9, wherein said first separating meansincludes a guide vane system (3, 7; 19, 23; 42) serving to force thematerial flow to be treated into a vorticously rotating motion thatsweeps along the interior wall of said separating chamber (4, 8; 20, 24;43) in order to separate the liquid and/or solids from the material flowunder the effect of a centrifugal force.
 16. An assembly according toclaim 9, which includes at least one additional separating means mountedinside said second separating means.
 17. An assembly according to claim9, wherein said first separating means and said second separating meansmounted inside said first separating means have downward return legsadapted co-axially inside one another, thus serving to return separatedsolids from each of said separating means into a common collectionspace.
 18. Assembly according to claim 17, characterized in that thereturn leg of any inner separating means in the vertical direction isadapted to extend higher than the top edge of the respectivelyconcentrically closest preceding outer separating means.
 19. Assemblyaccording to claim 9, characterized in that the guide vane system ofsaid separating means is adapted at least partially to the exterior sideand above of said separating means so as to extend in the radialdirection from the exterior side of said separating means so far inwardas to reach the interior space of the separating means.
 20. An assemblyaccording to claim 9, wherein said assembly includes deflecting and/orguiding means, said deflecting and/or guiding means including a tubularguiding element that is connected at least to the guide vane system (3,7; 19, 23; 42) of said second separating means and is adapted toenclosingly surround the outer surface of said second separating meansin a downward oriented manner, said deflecting and/or guiding meansserving to direct the material flow being treated in the uprightdirection from the bottom section of outer separating means to the guidevane system of the respectively subsequent inner separating means. 21.Assembly according to claim 20, characterized in that said deflectingand/or guiding means comprises guide vane members adapted to saidguiding means for guiding and deflecting the upright travelling flow.22. An assembly according to claim 9, said assembly having at least twoconcentrically mounted multiport cyclones as said first and secondseparating means, respectively, wherein a guide vane system of eachsuccessively inner multiport cyclone is adapted above a guide vanesystem of the respectively preceding outer multiport cyclone.
 23. Amethod for separating two phases from each other, said method comprisingpassing a material flow of a process, which material flow containsmaterial in a first phase and material in a second suspended ordispersed phase, into first separating means and, subsequently, into atleast second separating means, wherein the material in the suspended ordispersed phase is separated from the material in the first phase underthe effect of a centrifugal force, and at least one unit of the secondseparating means is a multiport cyclone which is adapted inside thefirst separating means and into which cyclone the material flow to betreated is fed via an infeed nozzle having an annular cross section,wherein a multiport cyclone is used as said first separating means,wherein the material flow to be treated is a gas flow containing solidsin suspended form discharged from a boiler used in energy generation asa flue gas from which particulate matter must be removed.
 24. A methodfor separating two phases from each other, said method comprisingpassing a material flow of a process, which material flow containsmaterial in a first phase and material in a second suspended ordispersed phase, into first separating means and, subsequently, into atleast second separating means, wherein the material in the suspended ordispersed phase is separated from the material in the first phase underthe effect of a centrifugal force, and at least one unit of the secondseparating means is a multiport cyclone which is adapted inside thefirst separating means and into which cyclone the material flow to betreated is a gas flow containing solids in suspended form, the gas flowfurther containing an exhaust gas of a drying process from whichparticulate matter must be removed, and said material flow is fed via aninfeed nozzle having an annular cross section, wherein a multiportcyclone is used as said first separating means.
 25. A method forseparating two phases from each other, said method comprising passing amaterial flow of a process, which material flow contains material in afirst phase and material in a second suspended or dispersed phase, intofirst separating means and, subsequently, into at least secondseparating means, wherein the material in the suspended or dispersedphase is separated from the material in the first phase under the effectof a centrifugal force, and at least one unit of the second separatingmeans is a multiport cyclone which is adapted inside the firstseparating means and into which cyclone the material flow to be treatedis a gas flow containing solids in suspended form, said gas flow furthercontaining an exhaust steam of a steam system from which liquid dropletsare removed, and said material flow to be treated is fed via an infeednozzle having an annular cross section, wherein a multiport cyclone isused as said first separating means.